The present invention relates generally to parcel sortation systems and, more particularly, to parcel sortation systems which support the parcels on transport units which are operable to discharge the parcels from the transport units to selected receiving ports. The transport units include carrier belts which are movable in a direction transverse to the conveying path of the transport units, in order to discharge the parcels to the selected destination port.
Crossbelt sortation systems are known and include a plurality of transport units which are movable along a conveying path between a package induct station and a discharge station or port. The crossbelt sortation systems are able to handle parcels of widely varying characteristics. For example, such systems may be used to sort magazines or envelopes at a postal center, frozen food articles, cellophane wrapped clothing articles, or the like. The crossbelt sortation systems are widely adaptable because the parcels are loaded onto carrier belts of the transport units. The carrier belts are movable generally perpendicular to the conveying path of the transport units, and the parcels are discharged from the units via movement of the carrier belts, after the transport unit has carried the parcel to the appropriate destination along the conveying path.
Additionally, parcels may be inducted to the transport units at various separate locations using a plurality of induction stations. However, only one package may be inducted onto a given transport unit at any time. If multiple induction stations are implemented, the throughput of the system may not be significantly enhanced unless one or more discharge stations are positioned between the induction stations to allow at least some of the transport units to empty their packages before arriving at the second induction station. Otherwise, a package may remain on a transport unit as it passes the second induction station, thereby precluding the transport unit from receiving another package at the second induction station.
It has been proposed to provide crossbelt conveyor units which can receive two packages on the belt of the conveyor unit. The objects or packages may then be discharged at appropriate stations. The crossbelt conveyor units may even be operable to discharge one package to one side of the conveyor unit and the other package to the other side of the conveyor unit. However, in order to properly position the packages at the appropriate side of the conveyor units, the packages need to be properly arranged and sequenced prior to being inducted onto the conveyor units. This requires an additional process of presorting the packages, which reduces the efficiency of the crossbelt sortation system. Also, the conveyor units are not able to receive one package from one side of the conveyor path and another package from an induction station at the other side of the conveyor path.
Double tilt tray units have also been proposed which receive and discharge packages at tilt trays positioned along opposite sides of the transport units. However, the packages must be properly arranged or sequenced prior to being inducted onto the units, since the packages cannot be transferred to or unloaded at the opposite side of the unit.
The present invention is intended to provide a dual belt crossbelt sorter which has a plurality of sorter or transport units movable along a conveying path. Each transport unit includes a pair of movable belts which are independently operable to receive a package from an induction station, transfer a package to the other belt of the transport unit, and/or discharge a package at an appropriate discharge ;station. The belts are longitudinally aligned on the sorter unit and movable in a direction generally transverse to the conveying path. The present invention thus provides significantly improved efficiency and throughput of the sortation system, without the need to presort the packages at the induction station.
According to a first aspect of the present invention, a crossbelt sortation system comprises a plurality of transport units which are movable along a conveying path between at least one induction station and at least one discharge station. Each transport unit has side-by-side driven carrier belts. Preferably, the side-by-side driven carrier belts are movable along a path which is orthogonal to the conveying path. Preferably, each of the carrier belts is at least occasionally independently driven from the other of the driven carrier belts. The carrier belts may be synchronously or simultaneously operable to load, transfer or discharge articles of varying sizes.
In one form, the crossbelt sortation system includes a control which is operable to determine a destination of packages at the induction station and an availability status of each carrier belt of each approaching transport unit. The control is operable to move a compatible article onto an appropriate carrier belt. The control may transfer an article on one belt to another belt of the transport unit in order to provide an available and compatible carrier belt for an article at the induction station.
According to another aspect of the present invention, a method of sorting articles comprises providing a crossbelt sortation system, which includes an endless chain of transport units with at least two side-by-side carrier belts, operating at least one induction station to position articles on either or both of the carrier belts, and operating the carrier belts to discharge the articles at an appropriate discharge station. The carrier belts may be independently operable, simultaneously operable and/or synchronously operable to load, transfer, discharge, and/or rotate articles at the carrier belts of one or more appropriate transport units.
In one form, the method further includes the steps of determining an availability status of each carrier belt and a destination of each article at the induction station. The availability status and destination are then compared to determine if the carrier belt and transport unit are compatible and available for each particular article. If a carrier belt is compatible with the article on the induction station, the carrier belt is selected or booked for that particular article. The comparison may be continuously performed for the status of each carrier belt of the transport units and destination of each article at a plurality of induction stations. The method may further determine whether an empty carrier belt has already been selected or booked by another induction station.
In another form, the size, shape and/or orientation of an article may be determined at the induction station. The article then may be loaded onto one or more carrier belts of one or more transport units. The belts may be synchronously activated to rotate, pivot and/or move the article onto both of the carrier belts of a transport unit or two adjacent transport units.
Therefore, the present invention provides a double width or dual crossbelt sortation system which is operable to receive parcels from an induction station at one or two of a pair of movable carrier belts on each conveyor or transport unit. The sortation system thus may receive packages at, transfer packages to, and/or discharge packages from either side of the sortation system. The sortation system effectively pre-sorts the articles by selecting an appropriate belt or belts for each package at induction stations along both sides of the conveyor path. The present invention thus provides improved throughput for the sortation system over the prior art.